Glass is generally known to be a typical amorphous substance, but crystallized glass having at least a part thereof crystallized is also known. The known crystallized glass is produced by adding an ion such as a titanium, gold, silver, copper, zirconium or fluorine ion or particles such as titanium dioxide as a crystal nucleus-forming material to glass-forming materials, melting the mixture, molding it, cooling the molded article, re-heating the article to a temperature at which the aforesaid ion or particles can easily move thereby forming a compound as a crystal nucleus in the inside of the glass, and further elevating the heating temperature to crystalline the glass. For example, a glass batch having a composition approximating crystals to be precipitated, for example eucryptite (LiO.sub.2.Al.sub.2 O.sub.3.2SiO.sub.2), is prepared, and 4 to 20% by weight of titanium dioxide (nucleating agent) is added. The mixture is melted and molded and then cooled. The glass is then reheated to form a nucleus while adjusting the temperature to a point about 50.degree. C. higher than the annealing point. Then, the heating temperature is adjusted to a point slightly lower than the transition point to crystallize glass.
Thus, the known process for production of crystallized glass requires a complex cycle of heating-cooling-heating, and moreover, since the conditions for forming the crystals are within a narrow range, the heating temperature must be strictly controlled. Consequently, this process has the defect that the productivity is low, and the cost of production is very high. Another defect is that because the types and proportions of the constituent components of the matrix glass must be selected with a range where crystallization easily occurs, the range of selection of the starting glass becomes narrow.
The present inventors worked extensively to develop a new process for producing crystallized glass, which would eliminate the aforesaid defects. The work finally led to the discovery that by using a specified organo-matallic polymer as a nucleating agent, crystallized glass having superior properties can be produced easily and economically.